Mechanical devices, such as spring-loaded devices, are commonly used to provide a resistance during some portion of a process. Such spring-loaded devices can be tailored to provide a necessary amount of resistance to accomplish the desired effect of the resistance. Sometimes, it is desirable for such spring-loaded devices to provide different amounts of resistance at different times of a process or depending on the type of item being processed. For example, in some processes it can be desirable for the spring-loaded device to provide enough resistance to stop an item being processed along a process path and then provide less resistance or drag to controllable allow the item being processed to move along the process path. However, such spring-loaded devices, such as a common torsion spring, typically cannot provide a dual amount or different amounts of resistances on an object without some other mechanical force acting on the spring-loaded device, such as by varying size of an item being processed when the spring-loaded device and process path are at a constant distance or by varying the distance between the spring-loaded device and the process path. Thus, it is often necessary to determine a spring force that will at least partially fulfill the intent of the different amounts of resistance.
As in sheet article processing, spring-loaded devices can be used to align the sheet articles for processing and regulate flow therethrough by providing resistance that is applied against the sheet article as it passes such spring-loaded devices. For example, a standard set of rotary, spring return, registration fingers is often used in sheet article processing to register, i.e., properly align, the sheet articles being processed but still permit the sheet articles to pass by the registration fingers. For instance, it is desirable for the fingers to have enough force to serve as a registration surface for an object, such as an envelope or document that is being fed into a processing station at a significant velocity. It is also desired that the force of the spring-loaded device be light enough for the object to subsequently be pushed through these same registration fingers without damage or deformation of the object due to excessive resistance of the registration fingers. However, even finding a compromise force to fulfill these dual purposes for the rotary spring, such as a simple torsion spring, on the rotating fingers, still does not provide satisfactory results that truly meets both of these requirements.
A need exists for systems and methods that can act operate in a manner similar to spring-loaded devices, but can provide better options for resistance.